In an interview on CNN's "State of the Union" aired Sunday, McCain said he didn't believe the war could be won without the number of troops requested by McChrystal, who has reportedly been at odds with Obama over the figure.

"I think the great danger now is a half-measure, sort of a -- you know, try to please all ends of the political spectrum," McCain said.

McCain's sentiments were echoed by other GOP leaders who took to the airwaves Sunday to encourage the president to heed the reported advice of his top commanders. Lindsey Graham told "Meet the Press" that "history will judge" the president based on his decision on Afghanistan.